P0300 on a 2021 Kia Telluride
P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.
Not your vehicle? See general P0300 info.
Most common causes on the 2021 Kia Telluride
Ranked from 337 NHTSA owner complaints filed for this vehicle.
- 1
Rod/main bearing wear from the documented 3.8L oil-consumption defect
High severityNumerous owners report the engine burning oil down to bearing-damaging levels; one owner explicitly linked a misfire diagnosis to the engine 'burning through every drop of oil,' and others found an inoperative cylinder or a failed rod bearing tied to low oil.
Reported in 5 NHTSA complaints - 2
Excessive oil consumption causing low compression (worn piston rings)
High severityMultiple owners document rapid oil loss between changes with no warning light, eventually causing rough running or complete engine failure; reduced ring seal directly lowers cylinder compression.
Reported in 4 NHTSA complaints - 3
Timing chain/tensioner wear disrupting valve timing
Medium severityOne owner's engine noise/oil-consumption complaint was diagnosed and repaired as a timing chain and tensioner problem; worn timing components throw off cam-to-crank timing and can misfire.
Reported in 1 NHTSA complaint - 4
Worn or fouled spark plugs
Low severityStandard wear item; check gap and condition, especially with oil-consumption contamination present on this engine.
Common causeParts:spark plug - 5
Failing ignition coil(s)
Medium severityA weak coil-on-plug unit produces a repeatable single-cylinder misfire; swap-test between cylinders to isolate.
Common causeParts:ignition coil - 6
Clogged or leaking direct-injection fuel injector
Medium severityAn injector delivering an incorrect fuel charge unbalances that cylinder's combustion.
Common causeParts:fuel injector - 7
Vacuum/intake air leak
Low severityUnmetered air leans out a cylinder enough to misfire, usually worse at idle.
Common cause - 8
EGR valve fault
Low severityExcess or mistimed EGR flow destabilizes combustion at idle and light load.
Common causeParts:EGR valve
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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.
Common symptoms
- Flashing or steady check engine light
- Rough idle
- Shaking under acceleration
- Loss of power
- Fuel smell from exhaust
What to check before replacing parts
Scan for cylinder-specific misfire codes
Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.
Inspect the spark plugs and coils
Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.
Check fuel trims for a vacuum leak
Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.
Verify fuel pressure
Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.
Compression / leak-down test if ignition and fuel check out
Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.
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